All termites eat cellulose in its various forms as plant fiber. Cellulose is a rich energy source (as demonstrated by the amount of energy released when wood is burned), but remains difficult to digest. Termites rely primarily upon symbiotic protozoa (metamonads) such as Trichonympha, and other microbes in their guts to digest the cellulose for them and absorb the end products for their own use. Gut protozoa, such as Trichonympha, in turn, rely on symbiotic bacteria embedded on their surfaces to produce some of the necessary digestive enzymes. This relationship is one of the finest examples of mutualism among animals. Most so-called higher termites, especially in the family Termitidae, can produce their own cellulase enzymes.

Because of the termite's reputation of eating wood and wrecking homes and buildings, which is greatly exaggerated in cartoons. A recent study by Australian scientists found that termites have been found to accumulate trace amounts of gold in their nests. According to the CSIRO, the termites burrow beneath weathered surface material which typically masks human attempts to find gold, and brings indicators of deposits to the surface. They believe that studying termite nests may lead to less invasive methods of finding gold deposits.